JP2000329222A - Control device for continuously variable transmission (cvt) - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a belt slip based on responsiveness when torque is abruptly changed and suppress the excessive belt pressing force for control during the steady state with little torque change by controlling two systems suitable for the changes of the operation state. SOLUTION: When a speed change is made to abruptly change torque, a selection function 20 selects a larger one of a first target Pe and a second target Pe according to the abrupt torque increase state. An ECU for a CVT determines the target line pressure from the engine output torque and gear shift ratio based on the selected target Pe and controls the actual line pressure to the target line pressure value. The line pressure is quickly increased to the large value, and a belt slip can be prevented. During the steady state with little torque change, the second target Pe with high precision is selected, the line pressure is controlled based on it, excessive pressing force is suppressed for control, and fuel consumption is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuously variable transmission control device for controlling a continuously variable transmission based on a parameter representing an engine output torque.

[0002]

2. Description of the Related Art A continuously variable transmission mounted on an automobile includes, for example, a continuously variable transmission (hereinafter referred to as CVT) in which a metal belt and a pair of pulleys (primary / secondary) having variable groove widths are combined. There is).

[0003] The CVT changes the winding diameter of a belt wound between both pulleys to change the speed of the engine input from the primary pulley, and transmits the rotation from the secondary pulley to the differential and running wheels. The speed ratio is controlled by adjusting the supply oil amount of the primary pulley.

[0004] The torque that can be transmitted between the primary pulley and the secondary pulley is determined by the force pressing the belt between these pulleys. For this reason, in the CVT, line pressure control is performed using a hydraulic pressure, for example, to press the belt with a secondary pulley without slipping. The higher the line pressure for pressing the belt, the higher the force for pressing the belt. However, if an excessively strong pressing force is applied to the belt, smooth movement of the belt is impaired. Therefore, the line pressure control is performed at a target line pressure set based on the input torque input to the CVT (torque output from the engine) and the gear ratio.

Conventionally, such line pressure control is based on a required value of the engine output required by the driver, for example, an average effective pressure (a value obtained by dividing the torque by the displacement, which is calculated based on the accelerator pedal opening and the number of engine speeds). The line pressure control is performed based on the torque information represented by the average effective pressure, using the value estimated by the parameter value of the engine output torque) as the engine output torque.

[0006]

By the way, the torque information obtained based on the accelerator opening is not the torque information when the fuel is burned and goes out of the engine, but is the torque information that is going to output before that time. The output timing is early and provides excellent responsiveness to shifting when the torque changes abruptly. However, since the torque information is a value estimated from a driver's request value, the accuracy is poor.

[0007] For this reason, in a steady state or the like where the change in torque is small, an excessive belt pressing force is frequently generated due to poor accuracy of the torque information, which affects the fuel consumption of the automobile.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. It is an object of the present invention to provide a responsiveness of a continuously variable transmission at the time of gear shifting when the torque changes abruptly. It is an object of the present invention to provide a control device for a continuously variable transmission which can achieve both control and suppression of generation of an excessive belt pressing force in a steady state of the continuously variable transmission having a small change in the speed.

[0009]

In order to achieve the above object, a control device for a continuously variable transmission according to the first aspect of the present invention has an output timing which is early but provides torque information having difficulty in accuracy. A first parameter value representing the engine output torque based on the rotation speed and the required value of the engine output required by the driver, and a parameter corresponding to the fuel injection amount to the engine, which provides torque information with a good accuracy but a late output timing. The continuously variable transmission is controlled based on one of the two parameter values, that is, the second parameter value representing the engine output torque from the value.

The control of the two systems enables the control of the continuously variable transmission suitable for the change of the driving state, and prevents the occurrence of excessive belt pressing force while preventing bell-slip. The driving fuel efficiency can be improved.

Preferably, the selecting means selects the larger one of the two parameter values when the torque rises sharply, and selects the second parameter value when in a steady state. According to this, it is possible to more reliably prevent belt slip and improve fuel efficiency.

Particularly, as the first parameter value, a parameter value representing a fuel property, a value corrected by a parameter value representing an environmental condition (atmospheric pressure, intake air temperature, etc.) in which the engine operates, and a second parameter value are used. By using the corrected value that subtracts the load of the auxiliary drive driven by the engine, a value close to the torque actually output from the engine can be obtained, so that the continuously variable transmission can be controlled with higher accuracy. You.

The control device for a continuously variable transmission according to the second aspect of the present invention is a simple control using the control system as it is,
In the fuel cut operation, in order to control the continuously variable transmission so as to withstand the deceleration load, during the fuel cut operation, a value in consideration of the load of the auxiliary equipment connected to the engine is output to the control means from the first parameter value. I did it.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on one embodiment shown in FIGS.

FIG. 1 schematically shows a control device of a continuously variable transmission system mounted on an automobile (vehicle). In FIG. 1, reference numeral 1 denotes a belt-type continuously variable transmission (hereinafter referred to as CVT).

The CVT 1 has a pair of pulleys 4 and 5 (primary / secondary) having a variable groove width and a combination of a fixed pulley 2 and a movable pulley 3 and wound between the pulleys 4 and 5. It has a belt member to be attached, for example, a metal belt 6.

The primary pulley 4 is connected to a crankshaft (output unit) of an engine, for example, an electronically controlled fuel injection engine 8 (hereinafter simply referred to as an engine) having an injector 8a, for example, via a forward / reverse switching unit 7. , The output from the engine 8 is input. An engine control means, for example, an engine ECU 9 is connected to the engine 8 so that the amount of fuel injected from the injector 8a is controlled in accordance with various operation modes set in the ECU 9 in advance. It is.

The secondary pulley 5 is connected, for example, via a differential 10 to running wheels of an automobile.

A hydraulic chamber 11 for moving the pulleys 3 is provided on the back of each movable pulley 3 of the pulleys 4 and 5.
Are formed. Each hydraulic chamber 11 has an oil passage 12
Through a hydraulic control means, for example, a hydraulic control valve system 13 configured by combining various control valves.
, So that the hydraulic pressure applied to both hydraulic chambers 11 by the system 13 can be adjusted.

The hydraulic control valve system 13 is connected to CVT control means, for example, a CVT ECU 14 (comprising a microcomputer). As is well known, a target gear ratio determined in advance according to the driving state of the vehicle is set in the CVT ECU 14, and the hydraulic chamber on the primary pulley 4 side is controlled by the hydraulic control valve system 13 based on the gear ratio. The amount of oil to 11 can be adjusted. Also CVT
The ECU 14 has a function of setting a target line pressure based on an input torque of the CVT 1 input by communication from the engine ECU 9, for example, an engine output torque, and a speed ratio determined in an operating state. Functions for controlling the oil pressure in the hydraulic chamber 11 on the secondary pulley 5 side are set so that the belt 6 is pressed by the secondary pulley 5 so as not to slip on the belt 6 by the line pressure control performed by these functions. By controlling the gear ratio and the line pressure performed by the CVT ECU 14, the winding diameter of the belt 6 wound between the pulleys 4 and 5 is changed to change the engine speed input from the primary pulley 4. The output is made from the secondary pulley 5.

The present invention is applied to the line pressure control of the CVT 1. According to the present invention, as shown in FIG. 2, a target average effective pressure (torque) representing an engine output torque is obtained from a required value of an engine output required by a driver, for example, information on an accelerator opening and information on an engine speed. A value obtained by dividing by a displacement: equivalent to a first parameter value, hereinafter referred to as a first target Pe) is obtained by the engine ECU 9, and the CV is obtained.
The first system A to be sent to the ECU 14 for T is combined with the second system B for obtaining a parameter value representing the engine output torque from the parameter value corresponding to the fuel injection amount to the engine 8 and sending the parameter value to the ECU 14 for CVT, and the output timing Is intended to compensate for the difficulty of the line pressure control performed based on the first target Pe (torque information) and the gear ratio, which is fast but has difficulty in accuracy.

Specifically, the engine ECU 9 includes, as the first system A, a map α based on the accelerator opening and the engine speed, and a first target corresponding to the accelerator opening and the engine speed based on the map α. A function of reading Pe and a function of sending the read first target Pe to the CVT ECU 14 are set. In other words, the first system A is a system that obtains torque information to be output in accordance with the driver's request.

Further, the engine ECU 9 provides, as a second system B, an average effective pressure Pe (hereinafter, referred to as a second target Pe) based on the injector pulse width of the fuel injection nozzle 8a and the engine speed for each different fuel property. A function of selecting various maps β to δ and maps of fuels to be used β to δ and reading a second target Pe corresponding to the injector pulse width and the engine speed from the map, the read second target Pe
Is sent to the CVT ECU 14. In other words, the second system B is a system that obtains torque information when the torque is output from the engine 1 according to the fuel injection amount. Since this torque information represents a torque generated when fuel is actually injected from the injector 8a and burned in consideration of the atmospheric pressure, the intake air temperature, and the like, a property opposite to the torque information obtained in the first system A is provided. In other words, the output timing is late, but the information has a property of high accuracy.

In order to obtain higher accuracy, the first
The first target Pe and the second target Pe obtained in the system A and the second system B have been corrected. Specifically, the engine ECU 9
A knock learning correction function 16 for correcting the first target Pe obtained from the map α based on the fuel property, an atmospheric pressure correction function 17 for correcting under the environmental conditions in which the engine 1 operates, and an intake air temperature correction function 18 is set to improve the accuracy of the first target Pe. EC for engine
U9 is provided with an auxiliary load correction function 19 for subtracting the load for driving the auxiliary equipment driven by the engine 1 from the second target Pe obtained from each of the maps β to δ.
The torque information obtained by subtracting the load of the auxiliary equipment is used as the CVT EC so as to have the same relationship as the power transmission when input to T1.
The data is input to U14. Thus, under the same conditions, both the value of the first target Pe to be output from now and the value of the second target Pe to be output at this moment are obtained.

The CVT ECU 14 compares the value of the first target Pe output from the first system A with the value of the second target Pe output from the second system B as shown in FIG. Then, a selection function 20 is set as selection means for selecting one of these values. Here, the selection function 20 is configured to determine whether the first target Pe and the second target P
e is selected, and the second target P
e is selected. Then, the selected value of the first target Pe or the value of the second target Pe is input to a program for functioning the line control, and the target line pressure is determined based on the Pe value and the gear ratio.

Only when the vehicle is decelerated and the fuel cut is performed, the load of the auxiliary equipment connected to the engine 1 is added to the value of the first target Pe obtained in the first system A to the engine ECU 9. Auxiliary equipment load correction function 21, cooling water temperature correction function 22 taking into account friction of engine 1
(Because the friction changes with the cooling water temperature), the CVT 1 is designed to withstand the deceleration load during the fuel cut operation. That is, the pressing force of the belt 6 is obtained in consideration of the load at the time of deceleration.

With such a configuration, the line pressure is rapidly increased during a shift in which the torque is rapidly increased, and the frequency of occurrence of an excessive belt pressing force is suppressed in a steady operation when the torque change is small. Power transmission can be performed.

To explain this point, during operation of the vehicle, the first target Pe obtained from the first system A based on the accelerator opening and the engine speed is a knock learning correction function 16 and an atmospheric pressure correction function, respectively. 17, corrected by the intake air temperature correction function 18, and transmitted to the CVT ECU 14. Also, from the second system B, the injector pulse width, which is a parameter value of the fuel injection amount calculated from the operating state of the engine, using a map selected from maps β to δ for premium gasoline and regular gasoline according to the properties of the fuel, The second target Pe obtained based on the engine speed is corrected by the accessory load correction function 19 and transmitted to the CVT ECU 14.

At this time, it is assumed that the driver suddenly depresses the accelerator pedal, and a gear shift is performed such that the torque increases sharply.

Then, the selection function 20 selects the larger one of the first target Pe and the second target Pe in accordance with the sudden increase in torque. The CVT ECU 14 determines the selected target P
The target line pressure is obtained from the engine output torque and the gear ratio based on e, and control is performed so that the actual line pressure becomes the target value.

Since the line pressure rises rapidly to meet such a large value, belt slip can be prevented.

On the other hand, when the vehicle is in a steady state with little change in torque, the second target Pe with high accuracy is selected and the line pressure is controlled based on the selected target Pe, so that the generation of excessive belt pressing force is suppressed, and fuel consumption is reduced. Can be improved.

Further, each target Pe of the first system A and the second system B represents a parameter value representing a fuel property (premium / regular, etc.) and an environmental condition (atmospheric pressure, intake air temperature, etc.) in which the engine 1 operates. The parameter value and the parameter value representing the auxiliary equipment load are corrected and a value close to the torque actually output from the engine 1 is used.
The control of VT1 is performed, and the frequency of occurrence of excessive belt pressing force can be further suppressed.

In addition, by simply considering the auxiliary equipment load in the first system A, the other system B does not need to be changed.
During the fuel cut operation, the CVT 1 can be controlled so as to withstand the deceleration load.

That is, it is assumed that the accelerator is released, the brake is depressed, the speed is reduced, and the fuel cut operation is started. At this time, the engine output torque estimated from the injector pulse width of the second system B is zero (or minus). The engine output torque estimated from the accelerator opening of the first system A becomes zero before that,
Since the auxiliary equipment driving load driven by the engine 1 is added to the zero value from the auxiliary equipment load correction function 21, the selection function 2
From 0, the first target Pe of the first system A in consideration of the accessory drive load is selected. The target line pressure is set based on the first target Pe, and the belt 6
And the line pressure control that can withstand the deceleration load of rotating the engine 1 and rotating the auxiliary equipment quickly starts up. Therefore, with the simple control just considering the auxiliary equipment load in the first system A, In response to the fuel cut operation, the control of the CVT 1 that can endure the deceleration load can be performed quickly.

In the embodiment, the accelerator opening is used as the driver's required value and the injector pulse width is used as the fuel injection amount. However, the present invention is not limited to this, and other parameters may be used. Nor.

[0037]

As described above, according to the first aspect of the present invention, responsiveness is ensured at the time of gear shifting when the torque changes abruptly, belt slip is prevented, and torque change is prevented. In the steady state of the continuously variable transmission with less torque, it is possible to perform shift control with an excessive pressing force suppressed, thereby improving fuel efficiency.

According to the invention described in claim 2, according to claim 1
In addition to the effects described above, the continuously variable transmission can be controlled by simple control so as to withstand a deceleration load during the fuel cut operation.
Moreover, since the auxiliary drive load is added to the engine output torque estimated based on the required value requested by the driver, the responsiveness is good, and when the fuel cut operation is started,
Immediately, there is an effect that the continuously variable transmission can be brought into a state that can withstand deceleration operation.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a control device for a continuously variable transmission according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining that the continuously variable transmission is controlled based on an engine output torque estimated from a driver request value and an engine output torque estimated from a fuel injection amount in the control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Continuously variable transmission 3,4 ... Pulley 6 ... Belt 14 ... CVT ECU (selection means, control means) α ... Map (first means) β ... Map (second means).

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme Court II (Reference) F16H 63:06 (72) Inventor Masato Tojo 3-33-8 Shiba 5-chome, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72 Inventor: Mitsuruzaki Kenji 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Atsushi Takeda 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation ( 72) Inventor Kazuchika Tajima 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Kenichi Nakamori 3-33-8 Shiba 5-chome, Minato-ku, Tokyo Mitsubishi Motors Corporation (72 ) Inventor Hiroki Asayama F-Term, 3-3-8, Shiba 5-chome, Minato-ku, Tokyo 3D041 AA21 AA33 AA54 AA66 AB01 AC20 AD02 AD09 AD10 AD14 AD48 AD52 AE07 AE08 AE36 AE39 AF09 3G093 AA06 BA15 BA19 CB07 DA01 DA04 DA05 DA06 DA10 DB08 DB25 EA05 FA07 FA10 FB01 3J052 AA14 CA21 EA04 FB31 GC13 GC34 GC44 GD02 GD03 HA11 L A01

Claims (2)

[Claims] 1. A first means for obtaining a first parameter value representing an engine output torque from a rotational speed of an engine and a required value of an engine output required by a driver, and an engine from a parameter value corresponding to a fuel injection amount to the engine. Second means for obtaining a second parameter value representing an output torque; selecting means for selecting one of the first parameter value or the second parameter value; control for controlling the continuously variable transmission based on the selected parameter value And a control device for the continuously variable transmission. 2. The fuel supply system according to claim 1, wherein the selection means outputs a value in consideration of a load of an auxiliary device connected to an engine from the first parameter value to the control means during a fuel cut operation. Control device for continuously variable transmission.